Combined Analyses of Ion Beam Synthesized Layers in Porous Silicon

A.R. Ramosa, F. Pasztic, Z.E. Horvathd, E. Vazsonyid, O. Condeb, M.F. da Silvaa, M.R. da Silvaa and J.C. Soaresa aITN-Inst. Tecnologico e Nuclear, Estr. Nacional 10, 2686-953 Sacavem, Portugal and Centro de Fisica Nuclear da Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1649-003, Lisboa, Portugal bFCUL-Fac. de Ciencias da Univ. de Lisboa, Dep. Fisica Ed. C1, 1749-016, Lisboa, Portugal cKFKI-Res. Inst. for Particle and Nuclear Physics, P.O. BOX 49, 1525, Budapest, Hungary dMTA-Res. Inst. for Technical Phys. and Materials Science, P.O. BOX 49, 1525, Budapest, Hungary

Full Text PDF

High dose ion implantation was used to form polycrystalline silicide films on porous silicon with different native concentrations of light impurities (C and O). Porous silicon layers several μm thick were implanted with 170 keV Cr+ ions to fluences of 3x1017 ions/cm2 both at room temperature and 450°C. Similar samples were implanted with 100 keV Co+ ions to fluences of 2x1017 ions/cm2 at room temperature, 350°C, and 450°C. The formed silicide compounds were studied by Rutherford backscattering spectrometry, elastic recoil detection, glancing incidence X-ray diffraction, and four point-probe sheet resistance measurements. Selected Co implanted samples were analysed by cross-section transmission electron microscopy. Results show that the light impurities were partially expelled from the forming silicide layer. Combining cross-section transmission electron microscopy with ion beam methods it was possible to show that, in the implanted region, the porous structure collapses and densifies during implantation, but the underlying porous silicon remains intact. The layer structure, as well as the quality and type of the formed silicide, were found to depend on the original impurity level, implantation temperature, and annealing.

DOI: 10.12693/APhysPolA.100.773 PACS numbers: 61.10.--i, 61.18.Bn, 61.43.Gt, 68.55.Ln